The most common causes of meningitis are viral infections that usually get better without treatment. However, bacterial meningitis infections are extremely serious, and may result in death or brain damage, even if treated.

Meningitis may also be caused by:

Chemical irritation

Drug allergies

Fungi

Parasites

Tumors

Most viral meningitis is due to enteroviruses, which are viruses that also can cause intestinal illness.

Many other types of viruses can cause meningitis.

Viral meningitis can be caused by herpes viruses, the same virus that can cause cold sores and genital herpes . However, people with cold sores or genital herpes are not at a greater risk of developing herpes meningitis.

Viruses that cause mumps and HIV can cause aseptic meningitis.

Recently, West Nile virus, spread by mosquito bites, has become a cause of viral meningitis in most of the United States.

Early diagnosis and treatment of bacterial meningitis is essential to prevent permanent neurological damage. Viral meningitis is usually not serious, and symptoms should disappear within 2 weeks with no lasting complications.

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